This invention relates to an exhaust system for two-cycle internal combustion engines and more particularly to an arrangement wherein the engine exhaust system provides a supercharging effect which is controlled so as to limit the likelihood of overheating and misfiring.
It is well known in multiple cylinder, two-cyle internal combustion engines to arrange the exhaust manifolding and firing order in such a way that the exhaust pulses of one cylinder are utilized to create a supercharging effect by generating a pressure pulse at the end of the scavenging stroke of another cylinder so as to insure that the fresh air fuel mixture taken into the cylinder will not be discharged and, furthermore, will be compressed thus providing a supercharging effect. However, such a supercharging effect can increase the heat load on the engine and may cause pre-ignition, knocking or other detrimental combustion characteristics.
It is, therefore, a principal object of this invention to provide an improved exhaust for a two-cycle, multiple cylinder internal combustion engine wherein some exhuast supercharging is obtained, however, the amount of exhaust supercharging is limited so as to reduce slightly the midrange torque and the heat load on the engine.